The present invention relates in general to space diversity radio receivers with spaced antennas, and, more specifically, to a diversity radio receiver system with proportional mixing of output signals from multiple tuners which are attached to a reconfigurable antenna signal combiner that combines antenna signals according to different phase combinations.
Space diversity radio receiver systems are a well-known means to reduce the effects of multipath distortion in mobile receivers. Multipath distortion is a localized effect resulting from interaction between signals from a transmitter which traverse different paths to reach a receiving antenna. By switching between spaced antennas in a diversity radio receiver, specific multipath events can be avoided since the spacing of the antennas helps insure that not both of the antennas will experience the same "short time delay" multipath events at the same time.
Co-pending application U.S. 09/103,131, entitled "Proportional Diversity Radio Receiver System," filed Jun. 23, 1998, which is incorporated herein by reference, discloses a proportional mixing system for reducing both short time delay multipath and long time delay multipath distortion mixing first and second tuner output signals proportionally in response to their signal strength signals and their detected long time delay multipath distortion. Such a proportional mixer, however, may still produce a noisy output signal when the antenna signals at both antennas are poor.
Since any particular broadcast could be received using either antenna at any particular time, each antenna in a mobile diversity system is designed to provide omni-directional reception. Thus, any noise present in the received signals which resulting from non-multipath sources, such as adjacent channel and co-channel interference and weak signal conditions, are present equally in both antennas and they cannot be removed by proportional mixing.